Semiconductors are very important products necessary in various industries. A semiconductor chip is produced, for example, by slicing a silicon monocrystal into a given thickness to produce a silicon wafer, and then forming various circuits etc. on this silicon wafer.
In such a process for producing semiconductor chips, there are widely used semiconductor producing/examining devices using, as a base thereof, a ceramic substrate such as an electrostatic chuck, a hot plate, a wafer prober, a susceptor and the like.
As such semiconductor producing/examining devices, for example, Japanese Patent gazette No. 2587289 and the publication of JP Kokai Hei 10-72260 disclose ceramic substrates used for these purpose.
All of the ceramic substrates disclosed in the above-mentioned publications and so on have a diameter of about 6 inches (150 mm) or a thickness of 8 mm or more.
However, as silicon wafers have been made large-sized in recent years, ceramic substrates having a diameter of 8 inches or more have been required.
In the process for producing a silicon wafer, it is necessary to use a ceramic substrate in which heating elements are embedded so as to heat the wafer. Furthermore, in order to make the heat capacity thereof small to improve the temperature following character thereof, it has been required to make the thickness thereof less than 10 mm.
According to the publication of JP Kokai Hei 7-280462, in this ceramic heater, the surface roughness of a face on which a silicon wafer is put or above which a silicon wafer is held to keep a given interval between the face and the wafer (referred to as a wafer-putting/holding face hereinafter) according to JIS R 0601 is set as follows: Rmax=less than 2 μm. The above-mentioned surface roughness of the face opposite thereof is adjusted to a roughness sufficient to cause diffused reflection of heat rays, that is Rmax=2 to 200 μm.